Documentation/linux_tv/media/v4l/vidioc-enum-dv-timings.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _VIDIOC_ENUM_DV_TIMINGS:
   4
   5 ***********************************************************
   6 ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS
   7 ***********************************************************
   8
   9 *man VIDIOC_ENUM_DV_TIMINGS(2)*
  10
  11 VIDIOC_SUBDEV_ENUM_DV_TIMINGS
  12 Enumerate supported Digital Video timings
  13
  14
  15 Synopsis
  16 ========
  17
  18 .. cpp:function:: int ioctl( int fd, int request, struct v4l2_enum_dv_timings *argp )
  19
  20 Arguments
  21 =========
  22
  23 ``fd``
  24     File descriptor returned by :ref:`open() <func-open>`.
  25
  26 ``request``
  27     VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS
  28
  29 ``argp``
  30
  31
  32 Description
  33 ===========
  34
  35 While some DV receivers or transmitters support a wide range of timings,
  36 others support only a limited number of timings. With this ioctl
  37 applications can enumerate a list of known supported timings. Call
  38 :ref:`VIDIOC_DV_TIMINGS_CAP` to check if it
  39 also supports other standards or even custom timings that are not in
  40 this list.
  41
  42 To query the available timings, applications initialize the ``index``
  43 field, set the ``pad`` field to 0, zero the reserved array of struct
  44 :ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>` and call the
  45 ``VIDIOC_ENUM_DV_TIMINGS`` ioctl on a video node with a pointer to this
  46 structure. Drivers fill the rest of the structure or return an ``EINVAL``
  47 error code when the index is out of bounds. To enumerate all supported
  48 DV timings, applications shall begin at index zero, incrementing by one
  49 until the driver returns ``EINVAL``. Note that drivers may enumerate a
  50 different set of DV timings after switching the video input or output.
  51
  52 When implemented by the driver DV timings of subdevices can be queried
  53 by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a
  54 subdevice node. The DV timings are specific to inputs (for DV receivers)
  55 or outputs (for DV transmitters), applications must specify the desired
  56 pad number in the struct
  57 :ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>` ``pad`` field.
  58 Attempts to enumerate timings on a pad that doesn't support them will
  59 return an ``EINVAL`` error code.
  60
  61
  62 .. _v4l2-enum-dv-timings:
  63
  64 .. flat-table:: struct v4l2_enum_dv_timings
  65     :header-rows:  0
  66     :stub-columns: 0
  67     :widths:       1 1 2
  68
  69
  70     -  .. row 1
  71
  72        -  __u32
  73
  74        -  ``index``
  75
  76        -  Number of the DV timings, set by the application.
  77
  78     -  .. row 2
  79
  80        -  __u32
  81
  82        -  ``pad``
  83
  84        -  Pad number as reported by the media controller API. This field is
  85           only used when operating on a subdevice node. When operating on a
  86           video node applications must set this field to zero.
  87
  88     -  .. row 3
  89
  90        -  __u32
  91
  92        -  ``reserved``\ [2]
  93
  94        -  Reserved for future extensions. Drivers and applications must set
  95           the array to zero.
  96
  97     -  .. row 4
  98
  99        -  struct :ref:`v4l2_dv_timings <v4l2-dv-timings>`
 100
 101        -  ``timings``
 102
 103        -  The timings.
 104
 105
 106
 107 Return Value
 108 ============
 109
 110 On success 0 is returned, on error -1 and the ``errno`` variable is set
 111 appropriately. The generic error codes are described at the
 112 :ref:`Generic Error Codes <gen-errors>` chapter.
 113
 114 EINVAL
 115     The struct :ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>`
 116     ``index`` is out of bounds or the ``pad`` number is invalid.
 117
 118 ENODATA
 119     Digital video presets are not supported for this input or output.
 120
 121
 122 .. ------------------------------------------------------------------------------
 123 .. This file was automatically converted from DocBook-XML with the dbxml
 124 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
 125 .. from the linux kernel, refer to:
 126 ..
 127 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
 128 .. ------------------------------------------------------------------------------